How to round sharp edges on curve?
I've experienced this sort of problem before, and while it doesn't work in all cases, one of the easiest / fastest methods I've found is this:


Convert the curve to a mesh.
Vertex bevel the corners - this gives you a nice control over the number of segments and width of the bevel
Convert back into a curve.


Your eventual curve will have a lot more control points near the corners (typically one per vertex after the bevel) and be a little more difficult to handle via the curve controls as a result, so I'd do this step last.  It's also reasonably destructive, but it works.